1. Field of the Invention
This invention relates to a process for the production of fatty alcohols, in which natural fats and oils are subjected to catalytic high-pressure hydrogenation in a tube bundle reactor.
2. Description of the Related Art
Fatty alcohols are normally produced from fatty acid methyl esters which are subjected to high-pressure hydrogenation in the presence of heterogeneous copper-chromium spinels, so-called Adkins catalysts. Although fatty acids may be used instead of the esters, this does mean that the stability of the catalysts has to meet particular requirements.
A particularly elegant method for the production of fatty alcohols is the direct hydrogenation of the natural fats and oils on which they are based. A process such as this also affords advantages by reducing the outlay on equipment and improving profitability because the starting materials used do not have to be so highly refined and, instead of the glycerol formed in the transesterification of fatty acid methyl esters, 1,2-propanediol is formed as a valuable secondary product.
The processes of the prior art have the disadvantage that the valuable 1,2-propanediol is not the only secondary product of the hydrogenation reaction. Instead, a complex mixture is obtained which, besides propane, propene, propanols and other substances, contains propanediols as one of many components so that isolation is out of the question on economic grounds. Accordingly, the profitability of processes for the direct hydrogenation of natural fats and oils is critically linked with the question of how selectively 1,2-propanediol is formed as a secondary product.
Accordingly, the problem addressed by the present invention was to develop a process for the direct hydrogenation of triglycerides which would be distinguished by particularly high selectivity for the formation of 1,2-propanediol as a secondary product.